The current single-phase iron core reactor is an assembly of a single “EI” shaped iron core active part and a single coil. This structure is suitable for the reactor whose operation voltage and capacity are below certain values respectively. However, when the voltage level and the capacity of a reactor reach a certain degree (e.g., a reactor in which the voltage level is 800 kV, and the capacity is 100000 kvar), as the reactor becomes larger and larger, the width and height of the reactor further increase, which brings difficulties to transportation of the reactor. In addition, since the creepage distance of the insulating member of the reactor is limited, it is not allowed that the voltage unlimitedly increases in a certain insulating distance. When the voltage level of the reactor further increases, the creepage voltage applied onto the insulating member correspondingly increases, which brings hidden danger to the reactor.